A liquid crystal display is a display of flat panel type commonly used at present, of which a thin film transistor liquid crystal display (TFT-LCD) has become a mainstream product.
In related arts, the liquid crystal display includes an array substrate and a color-filter substrate, in which the array substrate comprises a plurality of pixels arranged thereon in a matrix form, and each of the pixels includes a pixel electrode and a thin film transistor (TFT) connected to the pixel electrode as a switching element. With a common electrode located on the array substrate or on the color-filter substrate, the pixel electrode forms a liquid crystal capacitance, which applies electrical field to liquid crystal material. In addition, the pixel electrode may form a storage capacitance with a storage electrode formed on the array substrate so as to supplement the liquid crystal capacitance.
FIG. 1 is a schematic diagram for equivalent circuit of a unit pixel of the liquid crystal display in related arts. As shown in FIG. 1, when a TFT-LCD is in operation, on the array substrate, the gate ON voltage is firstly applied to a gate electrode g connected to gate line Gn and the TFT is switched on, thus a data voltage on a data line Dm for displaying an image signal is applied to the drain electrode d through the source electrode s. The drain electrode d is connected to a pixel electrode p, and the above data voltage is applied to the pixel electrode p through the drain electrode d so that a pixel electrode voltage is formed, where Cn is a storage electrode line. On the color-filter substrate, there is disposed a common electrode layer, and a voltage difference between the pixel electrode voltage on the pixel electrode p and the common electrode voltage V0 on the common electrode layer gives rise to a liquid crystal capacitance Clc, which is applied to liquid crystal molecules to make liquid crystal molecules orientated. Since a parasitic capacitance Cgd is formed between the gate electrode g and the drain electrode d, a sharp fluctuation in voltage when the gate line Gn is turned on and off is applied to the pixel electrode p with this parasitic capacitance Cgd, so that a kickback voltage ΔVp is generated on the pixel electrode voltage, thus accuracy of the pixel electrode voltage is influenced and a screen flicker is caused.